The sintering phenomenon or thermal deactivation of supported nanoparticles leads to lack of energetic floor space, resulting in their efficiency degradation affecting catalysis reactions. Scientists have proposed two mechanisms for sintering nanoparticles: particle migration and coalescence and Ostwald ripening.
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Regardless of a number of makes an attempt, the mixture of in situ stimulation and three-dimensional (3D) characterization couldn’t present a deep understanding of the sintering behaviors of nanoparticles. An article printed within the journalreported the design of a novel do-it-yourself X-Nano holder that built-in an in situ Joule heating and electron tomography (ET) to develop a quasi-four-dimensional transmission electron microscope (TEM) method.
The 3D characterization and statistical evaluation revealed the correlation between the placement and sintering conduct of the nanoparticles. Moreover, the quasi-four-dimensional TEM revealed that the exterior nanoparticles sintered through migration and coalescence, whereas the inner nanoparticles sintered Ostwald ripening.
The quasi-four-dimensional TEM developed within the current work could possibly be prolonged to different nanomaterials to have a deeper understanding of their 3D structural evolution beneath an exterior stimulus.
Benefit Of Quasi-4-Dimensional TEM Over Standard TEM Strategies
Metallic-based nanoparticles are sometimes utilized in catalytic reactions resulting from huge energetic websites owing to their excessive floor/quantity ratio. However, this benefit is a driving pressure for sintering, resulting in efficiency degradation in nanoparticles. Thus, having in depth information of sintering mechanisms is crucial to designing nanoparticles with excessive thermal stability.
Though similar location (IL) TEM can reveal the adjustments in similar nanoparticles beneath catalytic situations, an in situ holder with quasi-four-dimensional TEM serves as a handy TEM method to check the stimuli-based nanoparticle’s evolution in real-time.
Thus, systematic recording of the real-time sintering phenomena will help enunciate the sintering mechanism or reveal the intrinsic resistance property to the sintering phenomenon. Nevertheless, the two-dimensional (2D) projection of standard TEM imaging restricts the visibility of spatial data in a 3D object.
The knowledge on nanoparticles’ spatial location is crucial to analyzing their sintering conduct, which can’t be obtained primarily based on 2D projection via standard TEM. Therefore, integrating the quasi-four-dimensional TEM with ET launched the 3D characterization capability, together with the tilting perform.
Though two ET-specialized TEM holders had been beforehand reported and commercialized for 3D characterization, they lacked the power of in situ TEM characterization, limiting the understanding of nanoparticle’s 3D evolution throughout the sintering course of.
Sintering Behaviors of Supported Nanoparticles through Quasi-4-Dimensional TEM
Within the current research, gold nickel (AuNi) hybrid nanoparticle-supported carbon nanofiber (CNF) was used because the mannequin to check the sintering conduct. A do-it-yourself X-Nano holder helped draw data on the nanoparticle’s spatial location and corresponding sintering mechanism by integrating time dimension into ET.
In comparison with standard strategies like ILTEM and in situ TEM, which solely unexpectedly affirmed the placement of supported nanoparticles on the outer floor of CNF, the quasi-four dimensional-TEM characterization within the current work supplied spatial and temporal decision by the X-Nano holder. This facilitates the in depth research of the sintering conduct of nanoparticles beneath an exterior stimulus.
Moreover, lowering the time interval of tomogram acquisition utilizing ET will help obtain a better temporal decision, which captures the 3D evolution of nanoparticles resulting from sintering. The outcomes from quasi-four dimensional-TEM characterization revealed that the nanoparticles on the internal facet remained smaller than the exterior ones after sintering.
However, the dimensions distribution of inner nanoparticles was narrower than the exterior ones. Furthermore, the statistical outcomes of dimension change and nanoparticle’s sintering conduct had been analyzed by evaluating kinetic simulations with the experimental outcomes utilizing quasi-four-dimensional TEM.
The outcomes obtained from kinetic simulation supported the outcomes from the quasi-four-dimensional TEM characterization, confirming that the inner nanoparticles in CNF possessed robust interplay with surrounding carbon atoms and sintered through Ostwald ripening, whereas the weak interplay of exterior nanoparticles with the CNF floor resulted in sintering through migration and coalescence.
Thus, the quasi-four-dimensional TEM method adopted within the current research helped perceive the 3D evolution of nanoparticles when sintered beneath exterior stimuli. This methodology may be utilized to different nanomaterials to acquire data on location-dependent sintering conduct.
To summarize, the do-it-yourself X-Nano holder developed within the current research was built-in with an in situ Joule heating and ET-specialized quasi-four dimensional TEM. Thus, the developed built-in system helped research the sintering conduct of the nanoparticles beneath exterior stimulus in a quasi-four-dimensional TEM method.
The spatial location and the corresponding variation in dimension distribution through 3D characterization revealed that the inner nanoparticles had a smaller dimension and uniform distribution than their exterior counterparts. Moreover, the statistically kinetic evaluation and characterization utilizing quasi-four-dimensional TEM confirmed that the sintering mechanism of inner nanoparticles was through Ostwald ripening, whereas that of exterior nanoparticles was through migration and coalescence.
General, the current research revealed the crucial function of nanoparticles’ spatial location in understanding the sintering conduct of supported nanoparticles. The applying of the do-it-yourself X-Nano holder developed within the current research might be prolonged to a panorama of nanomaterials, contributing useful data on nanomaterial’s sintering kinetic concept.
Liang, C., Solar, D., Lv, H., Chu, W., Duan, Y., Bu, Y., Liu, J et al. (2022). Sintering Behaviors of Supported Nanoparticles Associated to Spatial Location by a Quasi-4-Dimensional TEM. Nano Letters.